About the only way "District 9" -- a bloody marvelous action movie that's part science-fiction allegory and part unabashed mayhem -- could get more in your face is if it was shot in 3D, so that the alien appendages and spurting blood could land in your lap.

South African director Neill Blomkamp nimbly sets up the backstory, in quick strokes and a documentary-like opening: 28 years ago, a UFO parked in the sky above Johannesburg, and just sat there for three months before any humans had the nerve to knock on the door. Inside the ship, the humans found about a million creatures living in malnourished squalor, apparently enslaved by the ship's now-absent overlords.

Flash-forward to today. The aliens, derisively nicknamed "Prawns" for their crustacean-like appearance, are living in a squalid shantytown called District 9, while the humans still haven't figured out how to make the aliens' technology -- especially their weapons -- work. On this day, the Multi-National Union, the peacekeeping group assigned to handle the alien refugees, has decided to move the aliens out of District 9 and into a new camp far away from Johannesburg.

The MNU official in charge of the move, a none-too-bright bureaucrat named Wikus Van De Merwe (Sharlto Copley, in a ballsy acting debut), tries to get the aliens to sign the paperwork that serves as the legal figleaf for this mass relocation. But when Wikus stumbles on a container of alien fluid that gets sprayed in his face, all hell breaks loose.

Blomkamp, who co-wrote the script with Terri Tatchell, delivers the action hard and fast and with plenty of curveballs. I haven't mentioned the Nigerian warlords who have set up a thriving black market in weapons and cat food (the Prawns' favorite food), or the military's secrets underlying the alien eviction, or the one friendly alien with whom Wikus forms an uneasy bond (think Nick Nolte and Eddie Murphy in "48 Hrs.," except Nolte's more lifelike).

All of the above is delivered at a furiously kinetic pace, with violence so immediate and visceral that it splashes blood and guts (fake, of course) right on the camera lens. But unlike the empty-headed violence of some summer blockbusters (I'm talking to you, Michael Bay), Blomkamp employs his action to create a compelling drama that's also a striking parable of the troubles of immigrants, refugees and mankind's inhumanity to fellow bipeds.

Blomkamp also has a secret weapon: His executive producer, Oscar-winning director Peter Jackson ("The Lord of the Rings"), whose New Zealand special-effects house Weta Workshop created the eye-grabbing special effects. Weta's wizards outdo themselves in creating surprisingly emotive and lifelike Prawns, contributing to the you-are-there authenticity that makes "District 9" work so effectively.

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